"The pattern for the accumulation was the same as in the control tomatoes.

Yeast gene

"We are excited about this approach, not only because it results in an increase in lycopene in tomato, but because we think it could be used to increase the phytonutrient content of other fruits and vegetables."

Randy Woodson, another Purdue expert, said: "When you just take lycopene as a drug it doesn't have the same effect.

"There is still a lot of biology to understand before we know why phytonutrients in food are so much more effective than if they are given as supplements."

To develop the lycopene-rich tomato, a researcher inserted a yeast-derived gene into tomato plants.

This gene affects the product of chemicals which help build compounds such as lycopene.

The inserted yeast gene was coupled to another gene which instructed it to work only in the fruits.

This is not the first GM project which has boosted the nutrient content of the tomato.

Other projects have boosted other tomato antioxidants such as flavonols and beta-carotene.